One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,4)(6,10)(11,12)(13,14)(15,25)(16,22)(17,23)(18,24)(19,21)(20,26)(27,28) involution — undirected(5,6)(7,11)(8,12)(9,10)(13,15,19,26)(14,20,21,25)(16,18,23,27)(17,24,22,28)(2,4)(5,7,9,8)(6,11,10,12)(14,21)(15,26)(16,23)(24,28)(1,2)(3,4)(5,7,9,8)(6,11,10,12)(13,16,19,23)(14,22,21,17)(15,18,26,27)(20,28,25,24)(5,8,9,7)(6,12,10,11)(13,17,19,22)(14,23,21,16)(15,24,26,28)(18,20,27,25)(13,18)(14,24)(15,23)(16,26)(17,25)(19,27)(20,22)(21,28) involution — undirectedA Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.